Buffalo bushmeat linked to brucellosis in Botswana

Among the people of Botswana, the wild African buffalo is the burger of choice. But this bushmeat could be making consumers sick: the animals harbour a pathogen that can cause severe fever in humans. The same pathogen is also common in some populations of buffalo in the US.

In 1974, researchers discovered that a bacterium from the genus Brucella, which causes brucellosis in humans, was widespread in herds of wild buffalo in Botswana. In response, the government built fences to isolate infected buffalo from domestic cattle, which can pass the disease to humans through meat, dairy products and close contact.

However, although the fences are effective and the pathogen has been eradicated from livestock, brucellosis still occurs in Botswanans. To find out why, Kathleen Alexander of Virginia Tech in Blacksburg and her team sampled over 1000 large wild animals, including buffalo, in Botswana. They found that about 6 per cent still carry antibodies against Brucella, suggesting that the disease remains in these wild populations.

Alexander's team suggests that hunting buffalo for bushmeat – both legally and illegally – may account for human cases. It is not just the hunters who risk infection: Alexander says that families will often buy bushmeat and process it together, possibly contracting the pathogen through the animal's blood.

The risk of catching brucellosis from wildlife has also been a longstanding debate in the US: the iconic Yellowstone bison have been blamed for infecting cattle with the disease, which can cause pregnant cows to abort. And in Florida, there are reports of hunters getting brucellosis from wild boar, says report co-author Jason Blackburn of the University of Florida in Gainesville.

"We need to make sure we have a clear understanding of how humans are interacting with wildlife and [identify] alternative sources of risk," says Blackburn. In African countries some cases of brucellosis may be misdiagnosed as malaria – the most common suspect for fever – because it may be falsely assumed only those who handle livestock risk exposure to Brucella.

Although brucellosis is rarely fatal in adults and can be treated with antibiotics, it may cause abortions. And in Botswana, about 40 per cent of the urban population is HIV-positive, says Alexander. For them, even a mild infection can be very serious.

If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.